Ok things are more clear now.
So I don't know if the camera works with UBports on the Meizu Pro5.
If this bug linked to the Pro5, then I'm sure it has been reported (as I understand you know).
In this case the issue is probably hard to fix.
If the bug has not been reported, you should do it (if not already).
And to help out people that come here to help, could you give us the link to the issue you discovered/submitted ?
This would be helpful.
Thinking about switching from canonical version of UT maybe some files in your home directory might have different rights.
And as @Keneda said, you might wanna try a full installation.
Save your personal data of course and then using the installer with the wipe option will give you a fresh start with UT.
Best of luck